15369 posts · Joined 2012. #2 · Mar 8, 2016. There are loads of things that cause antipollution faults but what i will say is this if you dont fix it properly then you WILL need a turbo. Reading and clearing faults does not help the fault you have is NOT saying your turbo is stuffed it is saying it overboosted and the ecu has shut the boost Answers to the above questions (which I found myself): 1. Yes, NOx sensor 1 readings should be 5-10 times higher than NOx sensor 2 readings. 2. No. 3. -. The replacement of the NOx sensor 1 solved the issue. One helpful video about this P20EE fault code (in the absence of other ECM and UDM faults) and how to troubleshoot: Hi I have a C3 1.4 8v First it has an anti-pollution fault on dash then I have a misfire on 4 replaced coil pack new plugs cleaned injectors and added current to make them squirt 3 jets. replaced oxygen sensor 1 and 2 changed round plugs changed round injectors still miss fire on 4 scratch head stuck screwdriver on all injectors all tapping Hi i have a citroen c5 2.2 hdi 2001 model is this obd or obd II ,i have a message anti pollution fault displaying and wondered if i could reset this, i have had the eloys fluid replaced 2 months ago, … Hi, just bought a Citroen C2 vibe 1.4 diesel 2008 plate last week. First really long journey this morning. Car started jittering a little at 65 mph then anti pollution warning on display and lost a lo … read more Pozdrav. Naime radi se o C5, 2003.g, 2.0 hdi bez fap-a. Prije par dana mi se upalilo antipollution fault greska. Auto malo ispuhao (bilo čađi u auspuhu, 90% voznja po gradu) i greska se vise nije palila. Jucer dođem kuci s posla ugasim auto i on ostane raditi jos jedno 2-3 sekunde nakon sta sam kljuc izvadio. Air Temp sensor being replaced hasnt removed the fault although it did for about 1 mile of driving when i picked it up. After 4 weeks of the Anitpollution message and engine management light coming on with about a total of 5 days where it wasnt coming up, I think its pretty safe to say its not that. remember please : some times ned to change catalytic converter and some times MAF filter need to replaceThis Peugeot 207 ECU is a very common failing unit t I have had the anti-pollution problem for over three years now. Citroen have failed spectacularly to fix this problem. I have spent about two thousand pounds trying to have it fixed - ie having everything replaced that can be replaced - and have ended up with a car that can barely do 70 mph unless there is a hill involved of course! Anyway, my grandmother just called me asking my advice. She just arrived home from Donegal (a 120 mile journey she does once a month to see her mother) and said that towards the end of her journey the car warned that the Depollution System is faulty. The car is a 2005 Citroen C4 Coupé 1.6 HDi VTR+ with 50,000 miles. wBNJcg.